(i) Technical Field
The present invention relates to focal plane shutters, imaging devices, and digital cameras.
(ii) Related Art
Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2002-043227 discloses a focal plane shutter equipped with first and second actuators that respectively drive a leading shutter and a trailing shutter. In such a shutter, after the leading shutter closes an opening and the trailing shutter recedes from the opening, the leading shutter moves away from the opening and the trailing shutter closes the opening, whereby an exposure operation is performed.
In such a shutter, in order to maintain a state where the leading shutter and the trailing shutter recede away from the opening, it is conceivable that first and second biasing members respectively bias the leading shutter and the trailing shutter to be away from the opening. In such a case, in the exposure operation, the direction in which the leading shutter is moved away from the opening by the first actuator is the same as the direction in which the leading shutter is biased by the first biasing member. However, the direction in which the trailing shutter is moved toward the opening by the second actuator is opposite to the direction in which the trailing shutter is biased by the second biasing member. Therefore, the load on the first actuator differs from that on the second actuator. Thus, for example, when the continuous shooting is performed for a predetermined period, the driving properties of the first and second actuators might be changed, so that the shutter speed might be changed.